This invention relates to a duplicating punch press of the same general type as disclosed in Brolund U.S. Pat. application Ser. No. 570,762, filed Apr. 23, 1975 and assigned to the assignee of the present invention. In such a press, holes are punched in a workpiece in locations determined by the positions of previously formed holes in a template.
The press includes a carriage having one or more clamps for holding the workpiece and adapted to be moved to locate the workpiece beneath the punch of the press. Movable with the carriage is a plunger or stylus which is adapted to be advanced into and retracted from the holes in the template.
When punching a hole in the workpiece, the carriage is moved until the stylus is alined with a selected hole in the template. The stylus then is advanced into the selected hole and serves to hold the carriage and the workpiece in a fixed position while the workpiece is being punched.
The press disclosed in the aforementioned application functions well in most instances but difficulty is encountered when heavy gauge workpieces are being punched. As the punch drives through a heavy workpiece, the frame of the press deflects and causes the punch to exert a horizontal force on the workpiece. The workpiece carriage is held in a stationary position by virtue of the stylus being located in the hole in the template and thus the horizontal force applied to the workpiece as a result of frame deflection can cause either shifting of the workpiece within the workpiece clamps or shifting of the clamps on the carriage. Such shifting changes the position of the workpiece relative to the carriage and thus the following holes will be punched at improper locations in the workpiece.